Well that's the basic func load test. Slight complication in handling entity codes, and some mucking about to get the indentation right. Still this passes now.

#
#       a little utility func to interpolate different strings
#       into the comment of the test func
#
        def junkify(junk):
                return """
function lua_func()
 print "lua stuff"
end
--
-- let's put some funky stuff in this comment
-- ${junk}
--
lua_func()
"""
        [Test]
        def save_func():
#
#               ok - I'm going to put some reserved chars
#               in this - they should appear in the save
#               file as entity codes
#
#               so let's have two versions of the junk string
#               one with the codes that we use to set up the Func
#               and one with entities that we use to check the saved data
#
                junk = """<>[]'"7;--"""
                junk_ent = """&lt;&gt;[]'"7;--"""
#
#               we set up the target string using the entity version
#
                target = detab("""
                        <func>
                                ${junkify(junk_ent)}
                        </func>
                """)
#
#               and initialise the func with vanilla junk
#
                f = Func()
                f.code = junkify(junk)

                sw = StringWriter()

                xs = XmlWriterSettings()
                xs.Indent = true
                xs.IndentChars = " "
                xs.NewLineChars = "\n"
                xs.OmitXmlDeclaration = true

                using r = XmlWriter.Create(sw, xs):
                        f.save(r)
I am feeling sorely tempted to go back to writing the app for a bit. I have plenty of test cases written in advance, and they're making my head hurt. Let's write some more actual code until I hit something that needs testing...